The objective of the research proposed in this application is to generate basic data relating to the control of spinal cord motor processes during active sleep in the adult cat. The animal model which will be employed to achieve this objective is the acute decerebrate cat in which atonia of the peripheral musculature is induced by the microinjection of carbachol, a cholinergic agonist, into the pontine reticular formation (the nucleus pontis oralis). Intracellular recordings will be obtained from spinal cord motoneurons, spinal cord interneurons that provide a monosynaptic inhibitory input to spinal cord motoneurons, and from neurons of the medullary nucleus reticularis gigantocellularis; the neurotransmitters modulating the excitability of these cells will be examined by recording intracellularly from them at the same time that neurotransmitter antagonists and agonists are ejected juxtacellularly. The proposed studies will (1) provide a description of the cholinergically activated mechanisms and neurotransmitters that produce atonia of the somatic musculature, and (2) establish new techniques and an experimental paradigm that combines the strategic advantages of the acute preparation with a pharmacologically induced pattern of motor control that appears identical to that which occurs spontaneously during active sleep in the intact cat.